The present invention relates to an apparatus and method for stabilizing a steering feel in a motor-driven power steering (MDPS), and more particularly, to an apparatus and method for stabilizing a steering feel in an MDPS, which receives a column torque of a steering wheel, filters noise components from the received column torque, and generates a compensation signal based on the column torque such that the steering wheel is stably returned.
A motor-driven power steering apparatus assists a steering force of a driver using torque of a motor, unlike an existing hydraulic power steering.
The motor-driven power steering apparatus is referred to as an MDPS or electronic power steering (EPS).
The MDPS receives a column torque from a torque sensor connected to a steering wheel, and calculates an assist amount of the motor by combining the received column torque with the speed of the vehicle, in order to improve steering performance.
The steering performance logic includes torque loop logic, high-frequency assist control (HFAC) logic, damping logic, and active returning logic. The torque loop logic is configured to set a main assist torque based on a booster output for a torque input. The HFAC logic is configured to reduce a sense of difference, felt by the driver due to the assist of the motor, and increase the output of the assist torque. The damping logic is configured to control vibration of the steering system. The active restoration logic is configured to increase the returning force of the steering wheel after rotation.
In particular, the damping logic serves to control the vibration of the steering system and stably control the returning speed when the steering wheel is restored.
However, the damping logic is subjected to a process of differentiating an input torque. During a rapid change, much glitch may occur, and the motor response speed of the MDPS may be decreased.
Furthermore, a phase margin may be significantly offset due to the differentiation process and a process of passing the input torque through a low pass filter. Thus, there is a limit to the magnitude and amount of noise which may be removed.
Thus, the MDPS in which various types of vibrations and noises may occur has a limitation in reducing the sense of difference felt by a driver.
The related art of the present invention is disclosed in Korean Patent Laid-open Publication No. 2012-0137087 published on Dec. 20, 2012 and entitled “System and method for controlling motor driven power steering”.